Effect and significance of NKG2D/RAE-1 pathway in the process of NK/T cells killing hypophysoma cells

SUN Qikai; MA Lixin; LI Zhenzhu; CHEN Zheng; LI Zefu

doi:10.3969/j.issn.1002-266X.2016.44.002

Abstract：Objective To observe the effect of NKG2D/RAE-1 pathway on mediating natural killer ( NK) cell and CD8 +T cell (both cells were referred to as NK/T cells) killing hypophysoma cells and to investigate the immune escape mechanism of hypophysoma from the cytological level .Methods The hypophysoma cell line AtT 20 was selected .The im-munofluorescent labeling method was used to detect the expression level of NKG 2D ligand RAE-1, its position and distribu-tion in the hypophysoma cells .NK/T cells were isolated by NK/T cell sorting kit , and NK/T cells were placed in the upper chamber of the Transwell chamber , the target cells AtT20 were placed in the lower chamber of the Transwell chamber and then were randomly divided into the control group and experimental group .The control group was co-cultured under normal conditions for 0, 4, 8, and 24 h.In the experimental group, the anti-RAE1 antibody was added to the culture medium , and the cells were co-cultured for 0, 4, 8, and 24 h.MTT assay was used to detect the inhibitory rate of cell proliferation at each time point .Results RAE-1 was clearly expressed in AtT 20 cell membrane , and there was a weak expression in the cytoplasm .The positive expression rate of RAE-1 protein in AtT20 cells was 100%, among which the strong expression rate was 30%(15/50), the moderate expression rate was 60%, the weak expression rate was 10%, and there was no neg-ative expression.In the control group, at 4, 8 and 24 h after culture, NK/T cell proliferation inhibition rate increased as compared with that at 0 h (all P<0.05).In the experimental group, the proliferation inhibition rate gradually increased at 0, 4, 8 and 24 h (all P<0.05), and at 8 and 24 h, the proliferation inhibition rates in the experimental group were sig-nificantly higher than those of the control group (all P<0.05).Conclusions NK/T cells kill the hypophysoma cells through NKG2D/RAE-1 pathway, meanwhile, RAE-1 has a negative feedback effect on NK/T cells and consequently in-hibits the killing activity of immune cells against the tumor cells .NKG2D/RAE1 pathway can be used as immunotherapy target for hypophysoma .